Interesting bug!
So…. I tested a product, verified everything working as it supposed to be. And then customer complains it is not working correctly. Usually that whats we get as initial reaction from customer. Upon several email back and forth we came to know that customers complain was right.
Customer complained that one of the product’s report is printing incorrect value on printed report, but when it preview it, it displays the value correctly. This is one of the weird thing I have heard so far. My initial reaction was, which was completely wrong, it is NOT possible to view some value and then print other value.
[I kind of develop reports for different program myself. I’m actually quite good at it even though I know only few types of report technology. From that knowledge I know that it is not possible.]
Lets see what was the problem...
When customer was printing the report, they noticed that the value of particular column displayed incorrect values on the printed report. The value was displaying “15.2”, “1.4” and “1.4” (as circled with red color in the below picture).
The correct value or the value displayed on print preview was “115.2”, “11.4” and “111.4”
What was happening is, when the report prints if the value is ”11” then it was printing as “1”, two 1 overlapping on the same location making the value as 1. So, if the value is “11.4” it was printing as “1.4” and for “111.4” as “1.4”. It does not do this for any other value, only the value that starts with 1’s. The value of 10, 9 , 101 everything was working.
When customer was seeing the value on print preview, it was a pdf preview and everything was fine. But for some peculiar reason when it is printed with SOME series of hp deskjet printer (which was the supplied printer with the product) was behaving this wired. It prints on laser jet fine, prints on newer printer fine as well.
Now what is my learning here as QA. We often do not have ideas how the software is made, what technology is used, what are the shortcoming of those particular technologies. With my test cases, I covered the print preview, prints and verify the values of some sample reports. During my testing, I did not come across any value that particularly starts with only “1”s. So I missed it. If you look into the incorrect picture you will see that the value displayed as “1.4”, the “1” is bold as it was printed three times on that same place. With some reporting tools/ technologies, sometimes it prints twice on same position making the thing bold/ thicker. Even if I came across that scenario, for the bold issue, I might have taken it as expected value.
Not everything you can calculate and verify. But at least, learning from this kind of incidents, you can educate yourself and look for this kind of issue on other products. The only thing we can assume, is we can’t assume in testing. It has to be based on expected values in every steps.
